make linux presubmit grpc_basictests_c_cpp_build_only a noop

tools/internal_ci/linux/pull_request/grpc_basictests_c_cpp_build_only.cfg

@@ -15,16 +15,11 @@
 # Config file for the internal CI (in protobuf text format)
 
 # Location of the continuous shell script in repository.
-build_file: "grpc/tools/internal_ci/linux/grpc_run_tests_matrix.sh"
+build_file: "grpc/tools/internal_ci/linux/pull_request/grpc_basictests_c_cpp_build_only.sh"
 timeout_mins: 60
 action {
   define_artifacts {
     regex: "**/*sponge_log.*"
     regex: "github/grpc/reports/**"
   }
 }
-
-env_vars {
-  key: "RUN_TESTS_FLAGS"
-  value: "-f basictests linux corelang --inner_jobs 16 -j 1 --internal_ci --build_only"
-}

tools/internal_ci/linux/pull_request/grpc_basictests_c_cpp_build_only.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+# Copyright 2023 The gRPC Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -ex
+
+# avoid slow finalization after the script has exited.
+source $(dirname $0)/../../../../tools/internal_ci/helper_scripts/move_src_tree_and_respawn_itself_rc
+
+# change to grpc repo root
+cd $(dirname $0)/../../../..
+
+source tools/internal_ci/helper_scripts/prepare_build_linux_rc
+
+echo "The grpc_basictests_c_cpp_build_only job on linux has been deprecated and is now a no-op."
+echo "The tests are running as bazelified tests under tools/bazelify_tests."
+echo "Note that the grpc_basictests_c_cpp job still runs on master (but not on PRs)."